#比较文件差异，天然去重
import sys
def divefile(fname1,fname2):
    with open(fname1) as fobj:
        data=set(fobj)
    with open(fname2) as fobj:
        bset =set(fobj)
    with open('/opt/aa.txt','w') as fobj:
        fobj.writelines(bset -data)
if __name__ == '__main__':
    divefile(sys.argv[1],sys.argv[2])